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klausb January 22, 2011 17:12

Discretizer: How to run a case in parallel?

does anyone use Discretizer and knows how to set it up to run a case in parallel on a 4 core processor?



ggruber January 23, 2011 13:21

Hello Klaus,

i compiled OpenFOAM an my machine.
Starting Discretizer with this shell script


. /home/username/OpenFOAM/OpenFOAM-1.6.x/etc/bashrc

starts Discretizer with this massage:

username@machine:~$ ./
Building on 2 cores

That's why i think the Solver (OpenFOAM) works on two cores.

Nothing special to do in Discretizer.

wyldckat January 23, 2011 15:12

Greetings to all!

OK, let me start off by saying that the best place for questions about Discretizer in this forum is here:
I say this because Björn Bergqvist, the author of Discretizer, can more easily keep track of feedback here in the forum if questions are made there. The other possibility is to send him directly an email with your questions. And I say ask him directly, because documentation is still limited, so only the author can be 90 to 100% sure of what works and doesn't.

Now, as far as I know, Discretizer still is far from completion. Currently it can act as training wheels and get you started, but it will only get you up to a certain point. So for things like launching simulations in multi-core/parallel simulations, you'll have to roll up your sleeves and get to the terminal and do things directly from there and with the help of your favourite text editor, acting as your faithful assistant.
Nonetheless, if the menu item "Solver->decomposeParDict" is enabled - after you've be setting up your simulation case and running with the settings you have defined - then that's the place where you can define how many sub-domains you can divide the mesh and what method should be used for the division procedure. And even then, if there is such an option to run in parallel, it should appear when you click on the menu item "Run->Run Simulation".

@ggruber: If it says:

Building on 2 cores
It applies only to building/compiling the code, not launching simulations or executing solvers in parallel :(
The capability to build in multiple cores is also very important, because in slow machines (1.0-2.0Ghz) machines, building the whole OpenFOAM toolbox with a single core, can take up-to 6 hours or more!! While with a state-of-the-art Intel i7 9xx 3.x GHz, or an AMD 1xxxT 3.x GHz machine, it can take only 30 minutes or even less!

Best regards and good luck!

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